Novel antibacterial drug target against Gram-negative bacteria: lipopolysaccharide transport protein LptDE and its inhibitors / 药学学报

The outer membrane composed predominantly of lipopolysaccharide (LPS) is an essential biological barrier for most Gram-negative (G-) bacteria. Lipopolysaccharide transport protein (Lpt) complex LptDE is responsible for the critical final stage of LPS transport and outer membrane assembly. The structure and function of LptDE are highly conserved in most G- bacteria but absent in mammalian cells, and thus LptDE complex is regarded as an attractive antibacterial target. In recent 10 years, the deciphering of the three-dimensional structure of LptDE protein facilities the drug discovery based on such "non-enzyme" proteins. Murepavadin, a peptidomimetic compound, was reported to be the first compound able to target LptD, enlightening a new class of antibacterial molecules with novel mechanisms of action. This article is devoted to summarize the molecular characteristics, structure-function of LptDE protein complex and review the development of murepavadin and related peptidomimetic compounds, in order to provide references for relevant researches.

Evaluación de la formación de biopelículas en aislamientos bacterianos y fúngicos por el método semicuantitativo de microtitulación con cristal violeta y el cualitativo de agar con rojo Congo / Assessment of biofilms formation of bacterial and fungal isolates using qualitative Congo red agar and semiquantitative crystal violet microtiter methods

Introducción. El 65 % de las infecciones humanas son producidas por bacterias o levaduras, cuya capacidad de formar biopelículas las hace más resistentes a los antimicrobianos y antifúngicos. Objetivo. Determinar la capacidad de formación de biopelículas en aislamientos bacterianos y fúngicos por medio de los métodos cuantitativo de microtitulación con cristal violeta y cualitativo de cultivo en agar con rojo Congo. Materiales y métodos. Con el método cuantitativo, se utilizaron los medios de cultivo infusión cerebro-corazón, tripticasa de soya y Müeller-Hinton para aislamientos bacterianos; para levaduras, se usaron caldo infusión cerebro-corazón y Sabouraud dextrosa. Para el método cualitativo de cultivo en agar, se utilizaron los mismos medios de cultivo más una solución con 3 % de rojo Congo y 10 % de dextrosa. Cómo método de referencia, se utilizó la propuesta de Stepanovic et al. Resultados. Se evaluaron 103 aislamientos bacterianos y 108 de levaduras. No es recomendable sustituir el caldo infusión cerebro-corazón por los caldos tripticasa de soya y Müeller-Hinton en el método cuantitativo, para evaluar la formación de biopelículas en los aislamientos bacterianos. El medio Sabouraud dextrosa, en caldo y agar, puede sustituir al de infusión de cerebro-corazón para evaluar la formación de biopelículas en levaduras, tanto por el método cuantitativo como por el cualitativo. Conclusión. El estudio de las biopelículas en el laboratorio de microbiología, a partir del método cualitativo de cultivo en agar con rojo Congo, es un procedimiento sencillo, rápido y de bajo costo, que proporciona información útil para el diagnóstico y la terapéutica de infecciones persistentes causadas por bacterias y levaduras.

Introduction. Sixty-five percent of human infections are caused by bacteria or yeasts able to form biofilms. This feature makes them more resistant to antimicrobials and antifungals. Objective. To determine biofilm formation capacity of bacterial and fungal isolates by quantitative crystal violet microtiter and qualitative Congo red agar methods. Materials and methods. Brain-heart infusion, trypticase soy broth and Müeller-Hinton culture media were used in bacterial isolates for the quantitative method; brain-heart infusion broth and Sabouraud dextrose were used for yeasts. The same culture media plus 3% Congo red and 10% dextrose were used to apply the qualitative method in agar. The proposal by Stepanovic, et al. was used as a reference method. Results. We evaluated 103 bacterial isolates and 108 yeasts isolates. We did not recommend substitute brain-heart infusion broth for trypticase soy and Müeller-Hinton broths for biofilm formation assessment in bacterial isolates using the quantitative method. Sabouraud dextrose medium, both broth and agar, can replace brain-heart infusion to assess biofilm formation in yeasts, quantitatively and qualitatively. Conclusion. The study of biofilms in the microbiology laboratory, using Congo red agar qualitative method, is a simple, fast, and inexpensive procedure that provides precise information for the diagnosis and treatment of persistent infections caused by bacteria and yeasts.

BRICS report of 2021: The distribution and antimicrobial resistance profile of clinical bacterial isolates from blood stream infections in China / 中华临床感染病杂志

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical bacterial isolates from bloodstream infections in China in 2021.Methods:The clinical bacterial strains isolated from blood culture from member hospitals of Blood Bacterial Resistant Investigation Collaborative System (BRICS) were collected during January 2021 to December 2021. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical Laboratory Standards Institute (CLSI). WHONET 5.6 was used to analyze data.Results:During the study period, 11 013 bacterial strains were collected from 51 hospitals, of which 2 782 (25.3%) were Gram-positive bacteria and 8 231 (74.7%) were Gram-negative bacteria. The top 10 bacterial species were Escherichia coli (37.6%), Klebsiella pneumoniae (18.9%), Staphylococcus aureus (9.8%), coagulase-negative Staphylococci (6.3%), Pseudomonas aeruginosa (3.6%), Enterococcus faecium (3.6%), Acinetobacter baumannii (2.8%), Enterococcus faecalis (2.7%), Enterobacter cloacae (2.5%) and Klebsiella spp (2.1%). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus aureus were 25.3% and 76.8%, respectively. No glycopeptide- and daptomycin-resistant Staphylococci was detected; more than 95.0% of Staphylococcus aureus were sensitive to ceftobiprole. No vancomycin-resistant Enterococci strains were detected. The rates of extended spectrum B-lactamase (ESBL)-producing isolated in Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis were 49.6%, 25.5% and 39.0%, respectively. The prevalence rates of carbapenem-resistance in Escherichia coli and Klebsiella pneumoniae were 2.2% and 15.8%, respectively; 7.9% of carbapenem-resistant Klebsiella pneumoniae was resistant to ceftazidime/avibactam combination. Ceftobiprole demonstrated excellent activity against non-ESBL-producing Escherichia coli and Klebsiella pneumoniae. Aztreonam/avibactam was highly active against carbapenem-resistant Escherichia coli and Klebsiella pneumoniae. The prevalence rate of carbapenem-resistance in Acinetobacter baumannii was 60.0%, while polymyxin and tigecycline showed good activity against Acinetobacter baumannii (5.5% and 4.5%). The prevalence of carbapenem-resistance in Pseudomonas aeruginosa was 18.9%. Conclusions:The BRICS surveillance results in 2021 shows that the main pathogens of blood stream infection in China are gram-negative bacteria, in which Escherichia coli is the most common. The MRSA incidence shows a further decreasing trend in China and the overall prevalence of vancomycin-resistant Enterococci is low. The prevalence of Carbapenem-resistant Klebsiella pneumoniae is still on a high level, but the trend is downwards.

Distribution and drug resistance of pathogenic bacteria of biliary tract infection in patients subjected to hepatobiliary surgery / 中国基层医药

Objective:To study the distribution and drug resistance of pathogenic bacteria of biliary tract infection in patients with hepatobiliary surgery.Methods:A total of 103 patients with biliary tract infection who received treatment in the Department of Hepatobiliary Surgery, Lanxi People's Hospital from May 2020 to October 2022 were included in this study. Their bile was cultured to analyze the distribution and drug resistance of pathogenic bacteria. The data were processed using the WHONET5.5 software system.Results:Fifty-eight pathogenic bacteria-positive samples were cultured from the bile of 103 patients with biliary tract infection, with a pathogenic bacteria-positive rate of 56.31%. Among 58 strains of pathogenic bacteria, 38 strains (65.52%) were gram-negative bacteria, mainly Escherichia coli and Klebsiella pneumonia, and 5 strains (8.62%) were fungal strains. Escherichia coli and Klebsiella pneumoniae were highly resistant to sulfamethoxazole-trimethoprim, ciprofloxacin, and other antibacterial drugs, and were completely sensitive to imipenem and meropenem. Enterococcus faecalis was mainly resistant to ampicillin and penicillin G,and it was completely sensitive to vancomycin and teicoplanin. Staphylococcus aureus was resistant to vancomycin, ciprofloxacin, cefotaxime, and other drugs. A total of 13 strains of ultrabroad-spectrum beta-lactamase bacteria were isolated from 25 strains of Escherichia coli and 7 strains of Klebsiella pneumonia, with the positive detection rate of 40.63%. Conclusion:The main pathogenic bacteria of biliary tract infection are Gram-negative bacteria, which are widely distributed and have serious drug resistance. In clinical practice, antimicrobial drugs should be reasonably selected according to the results of bile drug sensitivity tests.

Clinical Analysis of Colistin Sulfate in the Treatment of Hematonosis Infected by Multidrug-Resistant Gram-Negative Bacteria / 中国实验血液学杂志

OBJECTIVE@#To investigate the efficacy and safety of colistin sulfate in the treatment of hematonosis patients infected by multidrug-resistant (MDR) gram-negative bacteria (GNB), and discuss the possible factors that affect the efficacy of colistin sulfate.@*METHODS@#The clinical data of 85 hematologic patients infected with MDR GNB in the Soochow Hopes Hematonosis Hospital from April 2022 to November 2022 were collected and divided into clinically effective group with 71 cases and ineffective group with 14 cases according to the therapeutic efficacy of colistin sulfate. The age, gender, type of hematologic disease, status of hematopoietic stem cell transplantation, infection sites, type of pathogen, timing of administration, daily dose and duration of colistin sulfate, and combination with other antibacterial agents of patients in two groups were compared. Logistic regression was used to analyze on the meaningful variables to study the influencing factors of colistin sulfate. The adverse reactions of colistin sulfate were also evaluated.@*RESULTS@#There were no significant differences in age, gender, type of hematologic disease, hematopoietic stem cell transplantation status, infection sites and pathogen type between the effective group and the ineffective group (P>0.05). Compared with the medication time more than 7 days, meropenem used within 7 days in the clinical effective group, and timely replacement with colistin sulfate could obtain better efficacy, the difference was statistically significant (P=0.018). The duration of tigacycline before colistin sulfate did not affect the efficacy, and there was no significant difference in efficacy between the effective and ineffective groups. The therapeutic effect of colistin sulfate at daily dose of 500 000 U q8h was better than that of 500 000 U q12h, the difference was statistically significant (P=0.035). The time of colistin sulfate use in the clinically effective group was longer than that in the ineffective group, which had a statistical difference (P=0.003). Compared with the clinical ineffective group, the efficacy of combination regimens with colistin sulfate was better than that of colistin sulfate monotherapy, and the difference was statistically significant (P=0.013). Multivariate logistic regression analysis was performed on the indicators with statistical differences in the two groups of patients, which suggested that the use time of colistin sulfate (B: 2.358; OR: 10.573; CI: 1.567-71.361; P=0.015) and the combination of colistin sulfate (B: 1.720; OR: 5.586; CI: 1.210-25.787; P=0.028) were influential factors in the efficacy of colistin sulfate. During the treatment, the incidence of nephrotoxicity, hepatotoxicity and peripheral neurotoxicity were 5.9%, 1.2% and 1.2%, respectively.@*CONCLUSION@#The use of colistin sulfate improves the clinical efficacy of MDR GNB infections in hematological patients, and the timing of colistin sulfate administration and the combination of drugs are independent factors affecting its clinical efficacy, and the safety during treatment is high.

Causative Microorganisms Isolated from Patients with Intra-Abdominal Infections and Their Drug Resistance Profiles: An 11-Year (2011-2021) Single-Center Retrospective Study / 生物医学与环境科学（英文）

OBJECTIVE@#To investigate the distribution and antimicrobial susceptibility of causative microorganisms recovered from patients with intra-abdominal infections (IAIs).@*METHODS@#A total of 2,926 bacterial and fungal strains were identified in samples collected from 1,679 patients with IAIs at the Peking Union Medical College Hospital between 2011 and 2021. Pathogenic bacteria and fungi were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing (AST) was performed using the VITEK 2 compact system and the Kirby-Bauer method. AST results were interpreted based on the M100-Ed31 clinical breakpoints of the Clinical and Laboratory Standards Institute.@*RESULTS@#Of the 2,926 strains identified, 49.2%, 40.8%, and 9.5% were gram-negative bacteria, gram-positive bacteria, and fungi, respectively. Escherichia coli was the most prevalent pathogen in intensive care unit (ICU) and non-ICU patients; however, a significant decrease was observed in the isolation of E. coli between 2011 and 2021. Specifically, significant decreases were observed between 2011 and 2021 in the levels of extended-spectrum β-lactamase (ESBL)-producing E. coli (from 76.9% to 14.3%) and Klebsiella pneumoniae (from 45.8% to 4.8%). Polymicrobial infections, particularly those involving co-infection with gram-positive and gram-negative bacteria, were commonly observed in IAI patients. Moreover, Candida albicans was more commonly isolated from hospital-associated IAI samples, while Staphylococcus epidermidis had a higher ratio in community-associated IAIs. Additionally, AST results revealed that most antimicrobial agents performed better in non-ESBL-producers than in ESBL-producers, while the overall resistance rates (56.9%-76.8%) of Acinetobacter baumanmii were higher against all antimicrobial agents than those of other common gram-negative bacteria. Indeed, Enterococcus faecium, Enterococcus faecalis, S. epidermidis, and S. aureus were consistently found to be susceptible to vancomycin, teicoplanin, and linezolid. Similarly, C. albicans exhibited high susceptibility to all the tested antifungal drugs.@*CONCLUSION@#The distribution and antimicrobial susceptibility of the causative microorganisms from patients with IAIs were altered between 2011 and 2021. This finding is valuable for the implementation of evidence-based antimicrobial therapy and provides guidance for the control of hospital infections.

Evaluation of tegacycline regimens in treatment of gram-negative bacterial infections with Monte Carlo simulation / 中国临床药理学与治疗学

AIM: To evaluate the dose regimens of tegacycline for treatment of hospital-acquired pneumonia, complex abdominal infection and complex skin and soft tissue infection caused by Gram-negative bacterial infections with Monte Carlo model. METHODS: The minimum inhibitory concentrations (MICs) of tegacycline against Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae were collected from the CHINET in 2018. The target probability (PTA) and cumulative response fraction (CFR) of different regimens were calculated using Monte Carlo simulation based on PK/PD theory of tegacycline. RESULTS:In the treatments of HAP caused by gram-negative bacteria, when MIC≤0.5 μg / mL, the PTA of 50 mg q12h was greater than 90%, and when MIC≥1 μg / mL, PTA and CFR of 100 mg q12h were both greater than 90%, When MIC≥2 μg/mL, 50 mg q12h, 75 mg q12h and 100 mg q12h doses of PTA were less than 90%. In the treatment of cIAI, when MIC≤0.5 μg / mL, PTA of 50 mg q12h reached the target value, and when MIC=1 μg/mL, PTA of 100 mg q12h was greater than 90%. For complex skin and soft tissue infection, when the MIC≤0.25 μg/mL, the PTA of 75 mg q12h and 100 mg q12h was greater than 90%, and the PTA of the three administration regimen was less than 90%, when the MIC≥0.5 μg/mL. CONCLUSION:The dose of 50 mg q12h is more suitable for the treatment of HAP, when MIC>0.5 μg/mL, tigecycline may need 100 mg q12h to obtain the best clinical efficacy in the treatment of cIAI. For cSSSI. when MIC≤0.25 μg/mL, tigecycline can be administered with 75 mg q12h and 100 mg q12h. For the three types of infections caused by Escherichia coli, the conventional dose of tigecycline may achieve clinical efficacy.

Distribution and drug resistance characteristics of pathogens in recipients undergoing simultaneous pancreas-kidney transplantation / 器官移植

Objective To investigate the distribution and drug resistance characteristics of pathogens in donors and recipients undergoing simultaneous pancreas-kidney transplantation (SPK). Methods Clinical data of 231 pairs of donors and recipients undergoing SPK were analyzed retrospectively. The pathogens of samples from donors and recipients were identified by VITEK-2 analyzer, and drug sensitivity test was performed by K-B method. The source distribution and composition ratio of pathogens in donor and recipient samples, distribution characteristics of multi-drug resistant organism, infection of recipients and drug resistance characteristics of pathogens were analyzed. Results A total of 395 strains of pathogens were cultured from 1 294 donor samples, and the detection rate was 30.53%. Gram-negative bacteria mainly consisted of klebsiella pneumoniae, Gram-positive bacteria mainly comprised staphylococcus aureus, and fungi primarily included candida albicans, respectively. In total, 2 690 strains of pathogens were cultured from 10 507 recipient samples, and the detection rate was 25.60%. Gram-negative bacteria mainly consisted of pseudomonas maltophilia, Gram-positive bacteria primarily comprised enterococcus faecalis, and fungi mainly included candida albicans, respectively. Among 395 pathogens of donors, 15 strains of methicillin-resistant staphylococcus aureus (MRSA), 16 strains of extended-spectrum β-lactamase (ESBL) positive drug-resistant bacteria, 8 strains of carbapenem-resistant pseudomonas aeruginosa (CR-PA), 21 strains of carbapenem-resistant acinetobacter baumannii (CR-AB), 2 strains of carbapenem-resistant enterobacteriaceae (CRE) and 1 strain of multiple-drug/pan-drug resistant pseudomonas aeruginosa (MDR/PDR-PA) were identified. Among 2 690 strains of recipient pathogens, 73 strains of ESBL positive drug-resistant bacteria, 44 strains of CR-PA, 31 strains of CR-AB and 3 strains of MDR/PDR-PA were detected. One recipient developed donor-derived infection, 69 cases of pneumonia, 52 cases of urinary tract infection, 35 cases of abdominal infection and 2 cases of hematogenous infection were reported within postoperative 1 year. Gram-negative bacteria were resistant to certain antibiotics. Gram-positive bacteria were sensitive to vancomycin. Fungi were sensitive to amphotericin B. Conclusions Gram-negative bacteria are the main pathogens of SPK recipients, which are resistant to certain antibiotics. Empirical use of antibiotics can be delivered before culture results are obtained. Subsequently, sensitive antibiotics should be chosen according to the culture results to improve the survival rate of SPK recipients.

Evolution and development of potent monobactam sulfonate candidate IMBZ18g as a dual inhibitor against MDR Gram-negative bacteria producing ESBLs

A series of new monobactam sulfonates is continuously synthesized and evaluated for their antimicrobial efficacies against Gram-negative bacteria. Compound 33a (IMBZ18G) is highly effective in vitro and in vivo against clinically intractable multi-drug-resistant (MDR) Gram-negative strains, with a highly druglike nature. The checkerboard assay reveals its significant synergistic effect with β-lactamase inhibitor avibactam, and the MIC values against MDR enterobacteria were reduced up to 4-512 folds. X-ray co-crystal and chemoproteomic assays indicate that the anti-MDR bacteria effect of 33a results from the dual inhibition of the common PBP3 and some class A and C β-lactamases. Accordingly, preclinical studies of 33a alone and 33a‒avibactam combination as potential innovative candidates are actively going on, in the treatment of β-lactamase-producing MDR Gram-negative bacterial infections.

Temporal association between antibiotic use and resistance in Gram-negative bacteria / Associação temporal entre o uso de antibióticos e resistência em bactérias gram-negativas

The β-lactam/lactamase inhibitors (BLBLIs) combination drugs are considered an effective alternative to carbapenems. However, there is a growing concern that the increased use of BLBLIs may lead to increased resistance. This study determined the temporal association between the consumption of BLBLI and the antimicrobial resistance in Gram-negative bacteria. In this retrospective study, electronic data on the Gram-negative bacterial isolates, including A. baumannii, P. aeruginosa, E. coli, and K. pneumoniae from in-patients and susceptibility testing results were retrieved from the medical records of the clinical laboratory. A linear regression and cross-correlation analysis were performed on the acquired data. Increasing trends (p<0.05) in the consumption of BIBLI and carbapenem with a median use of 27.68 and 34.46 DDD/1000 PD per quarter were observed, respectively. A decreased trend (p=0.023) in the consumption of fluoroquinolones with a median use of 29.13 DDD/1000 PD per quarter was observed. The resistance rate of K. pneumoniae was synchronized with the BIBLI and carbapenem consumptions with a correlation coefficient of 0.893 (p=0.012) and 0.951 (p=0.016), respectively. The cross-correlation analysis against the consumption of BIBLI and meropenem resistant K. pneumoniae was peaked at 0-quarter lag (r=951, p=0.016). There was an increasing trend in the consumption of BLBLI and carbapenems. The increasing trend in the rates of resistance to piperacillin/tazobactam, in line with the increasing consumption of BLBLI, suggests that BLBLI has to be used with caution and cannot be directly considered as a long-term alternative to carbapenems.

Os medicamentos combinados de β-lactâmicos / inibidores da lactamase (BLBLIs) são considerados uma alternativa eficaz aos carbapenêmicos. No entanto, existe uma preocupação crescente de que o aumento do uso de BLBLIs pode levar ao aumento da resistência. Este estudo determinou a associação temporal entre o consumo de BLBLI e a resistência antimicrobiana em bactérias gram-negativas. Neste estudo retrospectivo, os dados eletrônicos sobre as bactérias gram-negativas isoladas, incluindo A. baumannii, P. aeruginosa, E. coli e K. pneumoniae de pacientes internados e os resultados dos testes de suscetibilidade foram recuperados dos registros médicos do laboratório clínico. Uma regressão linear e análise de correlação cruzada foram realizadas nos dados adquiridos. Foram observadas tendências crescentes (p < 0,05) no consumo de BIBLI e carbapenem com uma mediana de uso de 27,68 e 34,46 DDD/1000 PD por trimestre, respectivamente. Foi observada uma tendência de diminuição (p = 0,023) no consumo de fluoroquinolonas com uma mediana de uso de 29,13 DDD/1000 PD por trimestre. A taxa de resistência de K. pneumoniae foi sincronizada com os consumos de BIBLI e carbapenem com coeficiente de correlação de 0,893 (p = 0,012) e 0,951 (p = 0,016), respectivamente. A análise de correlação cruzada contra o consumo de BIBLI e K. pneumoniae resistente ao meropenem atingiu o pico no intervalo de 0 quarto (r = 951, p = 0,016). Houve uma tendência de aumento no consumo de BLBLI e carbapenêmicos. A tendência crescente nas taxas de resistência a piperacilina/tazobactam, em linha com o consumo crescente de BLBLI, sugere que BLBLI deve ser usado com cautela e não pode ser considerado diretamente como alternativa de longo prazo aos carbapenêmicos.

Temporal association between antibiotic use and resistance in Gram-negative bacteria

Abstract The -lactam/lactamase inhibitors (BLBLIs) combination drugs are considered an effective alternative to carbapenems. However, there is a growing concern that the increased use of BLBLIs may lead to increased resistance. This study determined the temporal association between the consumption of BLBLI and the antimicrobial resistance in Gram-negative bacteria. In this retrospective study, electronic data on the Gram-negative bacterial isolates, including A. baumannii, P. aeruginosa, E. coli, and K. pneumoniae from in-patients and susceptibility testing results were retrieved from the medical records of the clinical laboratory. A linear regression and cross-correlation analysis were performed on the acquired data. Increasing trends (p 0.05) in the consumption of BIBLI and carbapenem with a median use of 27.68 and 34.46 DDD/1000 PD per quarter were observed, respectively. A decreased trend (p=0.023) in the consumption of fluoroquinolones with a median use of 29.13 DDD/1000 PD per quarter was observed. The resistance rate of K. pneumoniae was synchronized with the BIBLI and carbapenem consumptions with a correlation coefficient of 0.893 (p=0.012) and 0.951 (p=0.016), respectively. The cross-correlation analysis against the consumption of BIBLI and meropenem resistant K. pneumoniae was peaked at 0-quarter lag (r=951, p=0.016). There was an increasing trend in the consumption of BLBLI and carbapenems. The increasing trend in the rates of resistance to piperacillin/tazobactam, in line with the increasing consumption of BLBLI, suggests that BLBLI has to be used with caution and cannot be directly considered as a long-term alternative to carbapenems.

Resumo Os medicamentos combinados de -lactâmicos / inibidores da lactamase (BLBLIs) são considerados uma alternativa eficaz aos carbapenêmicos. No entanto, existe uma preocupação crescente de que o aumento do uso de BLBLIs pode levar ao aumento da resistência. Este estudo determinou a associação temporal entre o consumo de BLBLI e a resistência antimicrobiana em bactérias gram-negativas. Neste estudo retrospectivo, os dados eletrônicos sobre as bactérias gram-negativas isoladas, incluindo A. baumannii, P. aeruginosa, E. coli e K. pneumoniae de pacientes internados e os resultados dos testes de suscetibilidade foram recuperados dos registros médicos do laboratório clínico. Uma regressão linear e análise de correlação cruzada foram realizadas nos dados adquiridos. Foram observadas tendências crescentes (p 0,05) no consumo de BIBLI e carbapenem com uma mediana de uso de 27,68 e 34,46 DDD/1000 PD por trimestre, respectivamente. Foi observada uma tendência de diminuição (p = 0,023) no consumo de fluoroquinolonas com uma mediana de uso de 29,13 DDD/1000 PD por trimestre. A taxa de resistência de K. pneumoniae foi sincronizada com os consumos de BIBLI e carbapenem com coeficiente de correlação de 0,893 (p = 0,012) e 0,951 (p = 0,016), respectivamente. A análise de correlação cruzada contra o consumo de BIBLI e K. pneumoniae resistente ao meropenem atingiu o pico no intervalo de 0 quarto (r = 951, p = 0,016). Houve uma tendência de aumento no consumo de BLBLI e carbapenêmicos. A tendência crescente nas taxas de resistência a piperacilina/tazobactam, em linha com o consumo crescente de BLBLI, sugere que BLBLI deve ser usado com cautela e não pode ser considerado diretamente como alternativa de longo prazo aos carbapenêmicos.

Temporal association between antibiotic use and resistance in Gram-negative bacteria / Associação temporal entre o uso de antibióticos e resistência em bactérias gram-negativas

Abstract The β-lactam/lactamase inhibitors (BLBLIs) combination drugs are considered an effective alternative to carbapenems. However, there is a growing concern that the increased use of BLBLIs may lead to increased resistance. This study determined the temporal association between the consumption of BLBLI and the antimicrobial resistance in Gram-negative bacteria. In this retrospective study, electronic data on the Gram-negative bacterial isolates, including A. baumannii, P. aeruginosa, E. coli, and K. pneumoniae from in-patients and susceptibility testing results were retrieved from the medical records of the clinical laboratory. A linear regression and cross-correlation analysis were performed on the acquired data. Increasing trends (p<0.05) in the consumption of BIBLI and carbapenem with a median use of 27.68 and 34.46 DDD/1000 PD per quarter were observed, respectively. A decreased trend (p=0.023) in the consumption of fluoroquinolones with a median use of 29.13 DDD/1000 PD per quarter was observed. The resistance rate of K. pneumoniae was synchronized with the BIBLI and carbapenem consumptions with a correlation coefficient of 0.893 (p=0.012) and 0.951 (p=0.016), respectively. The cross-correlation analysis against the consumption of BIBLI and meropenem resistant K. pneumoniae was peaked at 0-quarter lag (r=951, p=0.016). There was an increasing trend in the consumption of BLBLI and carbapenems. The increasing trend in the rates of resistance to piperacillin/tazobactam, in line with the increasing consumption of BLBLI, suggests that BLBLI has to be used with caution and cannot be directly considered as a long-term alternative to carbapenems.

Resumo Os medicamentos combinados de β-lactâmicos / inibidores da lactamase (BLBLIs) são considerados uma alternativa eficaz aos carbapenêmicos. No entanto, existe uma preocupação crescente de que o aumento do uso de BLBLIs pode levar ao aumento da resistência. Este estudo determinou a associação temporal entre o consumo de BLBLI e a resistência antimicrobiana em bactérias gram-negativas. Neste estudo retrospectivo, os dados eletrônicos sobre as bactérias gram-negativas isoladas, incluindo A. baumannii, P. aeruginosa, E. coli e K. pneumoniae de pacientes internados e os resultados dos testes de suscetibilidade foram recuperados dos registros médicos do laboratório clínico. Uma regressão linear e análise de correlação cruzada foram realizadas nos dados adquiridos. Foram observadas tendências crescentes (p < 0,05) no consumo de BIBLI e carbapenem com uma mediana de uso de 27,68 e 34,46 DDD/1000 PD por trimestre, respectivamente. Foi observada uma tendência de diminuição (p = 0,023) no consumo de fluoroquinolonas com uma mediana de uso de 29,13 DDD/1000 PD por trimestre. A taxa de resistência de K. pneumoniae foi sincronizada com os consumos de BIBLI e carbapenem com coeficiente de correlação de 0,893 (p = 0,012) e 0,951 (p = 0,016), respectivamente. A análise de correlação cruzada contra o consumo de BIBLI e K. pneumoniae resistente ao meropenem atingiu o pico no intervalo de 0 quarto (r = 951, p = 0,016). Houve uma tendência de aumento no consumo de BLBLI e carbapenêmicos. A tendência crescente nas taxas de resistência a piperacilina/tazobactam, em linha com o consumo crescente de BLBLI, sugere que BLBLI deve ser usado com cautela e não pode ser considerado diretamente como alternativa de longo prazo aos carbapenêmicos.

Randomized Control Study of Nebulized Colistin as an Adjunctive Therapy in Ventilator?Associated Pneumonia in Pediatric Postoperative Cardiac Surgical Population

Background:Ventilator?associated pneumonia (VAP) with multidrug?resistant (MDR) gram negative organisms is a common problem in intensive care unit (ICU). Aerosolized antibiotics enhance the efficacy of systemic antibiotics when added as adjuvants. Aim: The primary objective of the study was to compare the clinical and bacteriological outcome of patients with VAP who were administered intravenous (IV) antibiotics alone with those patients who were treated with adjunctive nebulized colistin (NC) along with IV antibiotics. The secondary objective was to study the occurrence of any adverse events during colistin nebulization. Settings and Design: The study was a prospective, randomized, double?blinded controlled study conducted at a tertiary?care teaching institution. Materials and Methods: Ninety?eight children from surgical ICU aged less than 12 years who were diagnosed with VAP due to gram negative bacteria following cardiac surgery were chosen and divided randomly into two groups. The experimental group (NC group) was treated with systemic antibiotics along with NC, whereas the control group (NS group) was administered systemic antibiotics with nebulized normal saline (NS). Clinical and bacteriological outcomes were noted. Statistical analysis was done using SPSS Version 20.0 software. The patient characteristics were compared using independent Student’s t test and Chi?square test. Results: There was a statistically significant reduction in the duration of mechanical ventilation, postoperative ICU and hospital stay (P < 0.05) in the NC group compared with the NS group. Conclusion: Aerosolized colistin may be considered as an adjunct to systemic IV antibiotics in pediatric patients with VAP due to gram negative bacteria susceptible to colistin.

A retrospective study of prevalence of multidrug resistant Gram-negative bacteria isolated from various clinical samples received at microbiology department of a tertiary care hospital

Background: Bacterial multidrug resistance (MDR) is particularly common in Gram-negative bacilli (GNB), with important clinical consequences regarding their spread and treatment options. The prevalence of drug-resistant cases is increasing globally. MDR has become a major problem for the treatment of bacterial infections and is becoming greatest challenge to public health. Quantification of the prevalence and the common antimicrobial coresistance patterns of MDR GNB (MDRGNB) isolates would have important implications for patient care. Aim and Objective: The aim of this study was to know the prevalence of multidrug resistant Gram-negative bacteria. Materials and Methods: This retrospective study was done from January 2021 to December 2021 at the Department of Microbiology, GMERS Medical College and Hospital, sola, Ahmedabad, Gujarat. Species identification was done by bacterial growth and standard biochemical reaction. Drug susceptibility testing of isolates was done by Kirby–Bauer disk diffusion method following Clinical Laboratory Standards Institute guidelines. MDR was defined as acquired resistance to at least one agent in three or more antimicrobial categories. Stool samples were not included in this study. Results: The 1-year records of a total of pathogens were studied. The highest number of pathogens were isolated from blood cultures (19%), followed by wound swabs (19%) then urine (10.3%) then sputum and pleural fluid (8.5%). The most frequently isolated pathogens were Klebsiella spp. (32.8%), Escherichia coli (28.8%), Acinetobactor spp. (20.8%), and Pseudomonas spp. (9.6%). Gram-negative isolates exhibited high overall resistance to all used antibiotic classes. All isolates showed 100% susceptibility to colistin. Conclusion: The results of the study showed that the most common MDR-GNB isolate is Klebsiella Pneumonii in intensive care units department in blood, pus, and sputum sample. The study findings will be part of a strict antibiotic stewardship (AMS) program and also indicate that AMS should begin at primary and secondary health-care centers to prevent antimicrobial resistance.

Isolation and Genetic Characterization of Gram-negative Bacteria from Different Fresh Retail Vegetables in Nigeria

Aim: The proportion of food borne disease outbreaks as a result of contaminated products has increased over the years. In this study, the genetic characteristics of antibiotic resistant Gram-negative bacteria from different fresh retail vegetables in Okada, Edo state Nigeria was investigated. Place and Duration of Study: In April-May 2021, the study was carried out in the Department of Pharmaceutical Microbiology, Igbinedion University Okada Edo state Nigeria. Methodology: One hundred and eight isolates were isolated from sixteen different retail leafy and salad vegetable samples. Recovered isolates from samples were identified using standard microbiological techniques. Species identification for ten randomly selected isolates was performed by Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and ribosomal multilocus sequence typing (rMLST). Antimicrobial susceptibility testing was performed using the Kirby-Bauer method for 15 antibiotics. Isolates were characterized by whole genome sequencing (WGS). Results: Species identification using MALDI-TOF-MS and ribosomal MLST assigned the 10 randomly selected isolates to four different species. Identified isolates include Proteus mirabilis, Proteus vulgaris, Acinetobacter baumanii and Klebsiella quasipneumoniae. Out of the 10 randomly selected isolates, 60% (6/10) were antibiotic resistant in the antibiotic susceptibility test. WGS data confirmed the identities of the isolates except Proteus vulgaris identified as P. terrae. More than one resistant determinant was detected on the draft genome sequence of 80% (8/10) of the randomly selected isolates especially the regulatory system modulating antibiotic efflux CRP and the plasmid mediated quinolone resistant determinant qnrD1. Significantly, one Proteus mirabilis isolate was sensitive to the antibiotics in the phenotypic testing but had resistance determinants present. Conclusion: This study provides genomic characterization of antibiotic resistant isolates from retail leafy and salad vegetables from Nigeria. Further study is important to understand the public health importance of such resistance and the amount of risk posed to human health by these resistant organisms.

Homeopathic medicine activity on the growth of Gram-negative bacteria

Homeopathy is a therapy that uses medications prepared with infinitesimal and dynamized dilutions. Current studies demonstrate in vitro activity of homeopathy on gram-positive bacteria such as Staphylococcus aureusand Streptococcus pyogenes. Among bacterial infections, urinary tract infection (UTI) is frequent, leads to later consequences and the main causal agent is Escherichia coli(E. coli). In other publications, it has been reported inactivity of homeopathy on E. colicultures. Due to the divergence in the literature, the objective of this study was to evaluate gram-negative bacteria growth under homeopathy treatment. Methods:The medicines Atropabelladona, Cantharis, Staphysagria,and Colibacillinumwere tested at 6CH, 12CH and 30CH inE. coliATCC 25922 and EPEC (Enteropathogenic Escherichia coli) ATCC 43887. Two hundred and fifty microliters of the medicines in alcohol 30% were incubated at 37ºC with 3 mL of Müller Hinton broth (MH), 10 µL of cultures at 0.5 Macfarland and subsequent dilution at 1/10. Bacterial growth was evaluated in a spectrophotometer at 600nm, in the periods of 6, 12,and 20 hours of incubation. Resultsand Discussion:The results showed no inhibition of bacterial growth under the studied conditions. These data corroborate with studies already published that indicate the absence of action of homeopathy on E. colicultures. Considering other studies, it can be suggested that homeopathic medicines have direct activity on the growth of Gram-positive and not Gram-negative bacteria. Evaluating the two bacterial groups, it is possible to assume that the difference in homeopathy activity could be linked to differences in the bacterial wall structure. This hypothesis should be evaluated by other tests with the same bacterialstrains. Conclusion:The homeopathic medicines tested have no direct activity on Gram-negative bacteria cultures.

Análisis comparativo de la actividad antimicrobiana de secreciones y excreciones larvarias de Calliphora vicina y Sarconesiopsis magellanica (Diptera: Calliphoridae) / A comparative analysis of Calliphora vicina and Sarconesiopsis magellanica (Diptera: Calliphoridae) larval secretions and excretions antimicrobial activity

Introducción. La creciente resistencia bacteriana a los antibióticos representa una amenaza mundial de salud pública. Las excreciones y secreciones larvarias derivadas de moscas necrófagas de la familia Calliphoridae podrían configurar una fuente promisoria para contrarrestar sus efectos. Objetivo. Comparar la actividad antimicrobiana de las excreciones y secreciones larvarias nativas, y de las mayores y menores de 10 kDa de Calliphora vicina y Sarconesiopsis magellanica (Diptera: Calliphoridae). Materiales y métodos. El bioensayo se hizo a partir de la técnica de turbidimetría y en el caso de las excreciones y secreciones menores de 10 kDa se determinó la concentración inhibitoria mínima (CIM). Resultados. Las excreciones y secreciones nativas y las menores de 10 kDa de C. vicina y S. magellanica, evidenciaron una potente actividad antibacteriana contra tres cepas de Staphylococcus aureus y cuatro bacterias Gram negativas, siendo las menores de 10 kDa más efectivas que las nativas en las dos especies de moscas evaluadas. Además, las menores de 10 kDa presentaron la misma efectividad, aunque en las pruebas de CIM se observó que las de S. magellanica fueron más potentes en todas las bacterias evaluadas, excepto contra la cepa de S. aureus ATCC 25923. Las mayores de 10 kDa no inhibieron el crecimiento bacteriano. Conclusión. Los resultados validaron, en general, que estas sustancias son fuente importante para el aislamiento y la caracterización de agentes antimicrobianos.

Introduction: The growing resistance to antibiotics worldwide represents a global threat to public health. The larval excretions and secretions derived from necrophagous flies from the Calliphoridae family could represent a promising source for counteracting their effects. Objective: To compare the antimicrobial activity of Calliphora vicina and Sarconesiopsis magellanica (Diptera: Calliphoridae) native excretions and secretions and those weighing more than 10 kDa and less. Materials and methods: We used the turbidimetry technique for the bioassay; we determined the minimum inhibitory concentration (MIC) for excretions and secretions weighing less than 10 kDa. Results: Calliphora vicina and S. magellanica native excretions and secretions and those weighing less than 10 kDa exhibited potent antibacterial activity against three Staphylococcus aureus strains and four Gram-negative bacteria; those weighing less than 10 kDa were more effective than the native ones in the two species of flies evaluated here. Furthermore, excretions and secretions weighing less than 10 kDa had the same effectiveness, except in the MIC trials where S. magellanica excretions and secretions weighing less than 10 kDa were more potent against all the bacteria evaluated, except for S. aureus ATCC 25923. Excretions and secretions weighing more than 10 kDa did not inhibit bacterial growth. Conclusions: These results potentially validate these substances as an important source for isolating and characterizing antimicrobial agents.

Nosocomial infections-related antimicrobial resistance in a multidisciplinary intensive care unit

Background: Intensive care units (ICUs) have become hubs of nosocomial infections worldwide. There has been a continuous rise in the development of antimicrobial resistance among ICU-acquired infections. Particularly, the Gram-negative bacteria implicated in ICU-acquired infections have become resistant to the majority of the antibiotics leading to a critical therapeutic problem. The present study was conducted to determine the antimicrobial resistance pattern of microorganisms causing nosocomial infections (ventilator- associated pneumonia [VAP], central line-associated bloodstream infection [CLABSI], and catheter-associated urinary tract infection [CAUTI]) in a multidisciplinary ICU. Materials and Methods: This prospective observational cohort study included the patients with ICU stay ? 48 h and any of the ICU-acquired infections: VAP, CLABSI, or CAUTI. The appropriate specimen was collected as per the standard procedure and cultured. The antimicrobial susceptibility of all the bacterial isolates recovered from the samples was performed according to the Clinical and Laboratory Standards Institute (CLSI) recommendations. The antimicrobial resistance data were analyzed using WHONET Microbiology Laboratory Database software 5.6 (WHONET 5.6). Results: Gram-negative microorganisms were the principal pathogens causing various infections in the ICU, out of which Pseudomonas aeruginosa and Klebsiella pneumonia were the commonest. Most of the Gram- negative bacteria showed a high degree of resistance to the majority of the antibiotics. Colistin was observed to be the most effective antimicrobial for Gram-negative pathogens followed by doripenem, meropenem, and tigecycline. The majority of Staphylococcus aureus isolates (71.4%) were methicillin-resistant S. aureus; however, all were sensitive to vancomycin and linezolid. Vancomycin-resistant Enterococci constituted 43% of Enterococcus isolates and were sensitive to linezolid and tigecycline. Conclusion: Antimicrobial resistance was very high among the pathogens causing nosocomial infections in the ICU, especially Gram-negative bacteria demonstrated a substantially high degree of resistance to the majority of the antibiotics. Antibiotic stewardship will help control the emergence of multidrug-resistant microbes.

Differences in organ dysfunction between gram-positive and gram-negative bacteria-induced sepsis in rats / 中华麻醉学杂志

Objective:To evaluate the differences in organ dysfunction between gram-positive and gram-negative bacteria-induced sepsis in rats.Methods:Fifty-two adult male Sprague-Dawley rats, weighing 340-380 g, aged 15-18 weeks, were divided into 3 groups using a random number table method: control group (C group, n=12), G - bacteria group ( n=20), and G + bacteria group ( n=20). The G + and G - septic models were developed by intraperitoneal injection of inactivated Staphylococcus aureus and Escherichia coli suspension in G + and G - bacteria groups, respectively.The survival status within 36 h after injection of inactivated bacteria was recorded.Mean arterial pressure (MAP), platelet count (Plt), oxygenation index (OI) and serum concentrations of tumor necrosis factor α (TNF-α), cardiac troponin T (cTnT), total bilirubin (TBIL), creatinine (Cr), neuron-specific enolase (NSE) and lactic acid (Lac) were measured at 6, 12, 24 and 36 h after injection of inactivated bacteria.Fear conditioning test and open field test were performed at 12 and 36 h after injection of inactivated bacteria.The apoptosis rate of neurons in hippocampal CA1 area was measured by TUNEL, and the permeability of blood-brain barrier was measured by Evans blue method.The histopathological changes of lung, heart, kidney and brain tissues were examined at 36 h after injection of inactivated bacteria. Results:Compared with C group, the number of crossing grids and percentage of time spent freezing were significantly decreased, the apoptosis rate of neurons and permeability of blood-brain barrier were increased, and the survival rate was decreased in G - bacteria group and G + bacteria group ( P<0.05); the serum TNF-α concentration was significantly increased in G + bacteria group, and the serum cocentration of OI was significantly decreased, and the serum concentrations of cTnT, Cr, TNF-α and Lac were increased in G - bacteria group at 6 h after injection of inactivated bacteria ( P<0.05); the serum concentrations of cTnT, Cr, NSE, TNF-α and Lac in G + bacteria group and serum concentrations of cTnT, Cr, TNF-α and Lac in G - bacteria group were increased, and the OI, MAP and Plt were decreased at 12 h after injection of inactivated bacteria in both groups ( P<0.05); the serum concentrations of cTnT, TBIL, Cr, NSE, TNF-α and Lac were increased, and OI, MAP and Plt were decreased at 24 and 36 h after injection of inactivated bacteria in G + bacteria group and G - bacteria group ( P<0.05). Compared with G + bacteria group, the serum concentrations of TNF-α and cTnT and apoptosis rate of neurons were significantly decreased at 12 h after injection ( P<0.05); the serum concentrations of TNF-α and Lac were significantly increased, the serum concentrations of cTnT, OI, MAP and Plt were decreased at 24 h after injection of inactivated bacteria ( P<0.05); the serum concentrations of Cr, NSE, TNF-α and Lac were significantly increased, OI, MAP and Plt were decreased, and the percentage of time spent freezing, apoptosis rate of neurons and permeability of blood-brain barrier were increased at 36 h after injection of inactivated bacteria in G - bacteria group ( P<0.05). Conclusions:Early respiratory dysfunction and multiple organ failure often occur in G - bacteria sepsis, while G + bacteria sepsis is more likely to cause early circulatory and neurological dysfunction, and G - sepsis presents with more serious organ damage and high fatality rate as the disease progresses.

The health facility as a risk factor for multidrug-resistant gram-negative bacteria in critically ill patients with COVID-19

Abstract Background The relationship between Multidrug Resistant-Gram Negative Bacteria (MDR-GNB) infection and colonization in critically ill COVID-19 patients has been observed, however, it is still poorly understood. This study evaluated the risk factors for acquiring MDR-GNB in patients with severe COVID-19 in Intensive Care Units (ICU). Methods This is a nested case-control study in a cohort of 400 adult patients (≥ 18 years old) with COVID-19, hospitalized in the ICU of 4 hospitals in the city of Curitiba, Brazil. Cases were critical COVID-19 patients with one or more MDR GNB from any surveillance and/or clinical cultures were taken during their ICU stay. Controls were patients from the same units with negative cultures for MDR-GNB. Bivariate and multivariate analyses were done. Results Sixty-seven cases and 143 controls were included. Independent risk factors for MDR bacteria were: male gender (OR = 2.6; 95% CI 1.28‒5.33; p = 0.008); the hospital of admission (OR = 3.24; 95% CI 1.39‒7.57; p = 0.006); mechanical ventilation (OR = 25.7; 95% CI 7.26‒91; p < 0.0001); and desaturation on admission (OR = 2.6; 95% CI 1.27‒5.74; p = 0.009). Conclusions Male gender, desaturation, mechanical ventilation, and the hospital of admission were the independent factors associated with MDR-GNB in patients in the ICU with COVID-19. The only modifiable factor was the hospital of admission, where a newly opened hospital posed a higher risk. Therefore, coordinated actions toward a better quality of care for critically ill COVID-19 patients are essential.